1. Colloidal Nano-Silica as a Concrete Treatment: Laboratory and Case Studies
LOGO
A. Brent Rollins, Director Civil Engineering Materials Research Laboratory

2. Colloidal Nano-Silica Defined
Introduction
Colloidal Nano-Silica Defined
Small particles consisting of an amorphous SiO2 core with hydroxylated surface.
Typically between 1 and 500 nm
Insoluble in water
Small enough to remain suspended without settling.
Sufficiently small enough to not be affected by gravitational forces
Sufficiently large enough to show marked differences from true solutions.

3. Introduction
How Colloidal Silica Works
Example: Portlandite Consumption by CNS
The principal components of Portland cement pastes are Calcium Silicate Hydrate (C-S-H) gel and Portlandite (calcium hydroxide).
Pozzolanic additives contribute to strength development by reacting with Portlandite to generate more C-S-H.
Colloidal silica is an excellent source of Pozzolanic reactions, its small size making it many times more effective than silica fume.
(Hou, 2013)

4. Introduction
How CNS Works
Capillary Formation in Concrete
Capillary Voids Example
When concrete is first placed, it is at its greatest volume, containing water needed for the chemical reaction (hydration) and evaporable and in-evaporable water.
Evaporable water leaves the concrete, forming capillary voids as it exits. .
Brameshuber,2008

5. Introduction
How CNS Works
Reaction Products
Effects of Filling Capillary Pore Space
Reaction products begin to occupy pore space, effectively reducing void content.
In post-treated CNS applications, the pore space filled is generally capillary pore space.
As capillary pore space is filled, it is easy to imagine that many hardened properties of concrete are subsequently improved..

6. Examination of CNS Effects on Concrete: Overview
Introduction
Examination of CNS Effects on Concrete: Overview
Effects on Drying Shrinkage
Effects on Compressive Strength
Effects on Permeability A B C
Values in the Academic Literature for CNS
Values for post-applied laboratory experiments
Values in the Academic Literature for CNS
Values for post-applied laboratory experiments
Values in the Academic Literature for CNS
Values for post-applied laboratory experiments
Corrosion Modeling
Based on Reduced
Permeability
Case Study: Port of Marseille, France E D
Demonstration of the Utility of Reduced Permeability in Corrosion Life Cycle Modeling
Details of Recent Successful Placement of CNS-treated concrete at the Port of Marseille, France

7. Compressive Strength Effects
From the Literature
On plain cement concretes (from Rashad)

8. Compressive Strength Effects
From the Literature
On blended cementitious concretes (from Rashad)

9. Compressive Strength Effects
From the Laboratory, Post-Applied CNS

10. Compressive Strength Effects
From the Laboratory, Post-Applied CNS (2015)

11. Effects on Drying Shrinkage
From the Academic Literature
From Du, 2015

12. Effects on Drying Shrinkage
From Laboratory Testing

13. Effects on Permeability
From the Academic Literature
From Rashad

14. Effects on Permeability
From the Academic Literature
From Pourjavadi, et al

15. Effects on Permeability
From Laboratory Testing

16. Effects on Permeability
From Laboratory Testing

17. Effects on Permeability
From Laboratory Testing
(DIN 1048 Testing, Middle Tennessee State University)

18. Effects on Permeability
From Laboratory Testing – Hydrostatic Pressure Resistance

19. Corrosion Life Cycle Modeling

20. 25% Fly ash plus spray-applied CNS and integral CNS
100% cement plus
Spray-applied CNS
And integral CNS
25% Fly ash plus
Spray-applied CNS
100% cement plus spray- applied CNS
25% Fly ash
100% Cement

21. Test Case: Port of Marseille, France
A 70m long sporting quay was scheduled for concrete replacement in 2014.
The Port Authority wanted to try spray-applied CNS to reduce the permeability and the number of contraction joints.
I recommended that the number of joints be reduced from 7 to 3.
The Port Authority cut zero joints. One year later, no drying shrinkage cracks are visible.

22. Spray-Applied CNS application, Port of Marseille
Application of the spray- applied CNS is relatively easy, with no environmental impacts.
Spray-applied CNS can be used for new concrete or for remediation of old concrete.

23. Application details
Greatest success has been obtained by treating concrete to rejection.
Ionic attraction pulls CNS deeply into capillaries, typically penetrating between 50 and 300 mm.
Penetration depth depends on the permeability of the concrete.
Ionic attraction allows for application on vertical or overhead surfaces.

24. Conclusion
CNS has been shown in the academic literature to be a promising approach to extending the lifespan of concrete.
UTC laboratory testing has demonstrated effects of CNS on concrete compressive strength, permeability, and drying shrinkage.
Finally, test cases including the Port of Marseille, France, have demonstrated the ease of application and effectiveness of CNS.

25. References
Numerous references were used for this presentation. Please contact me at for a complete list of referenced works or with any questions you may have.